The present invention relates to a method of forming a multicolor image and an apparatus therefor.
It has been customary in the imaging art to uniformly charge a photoconductive element, scan the photoconductive element to electrostatically form a latent image thereon, and developing the latent image by reversal to thereby form a toner image. To form a multicolor image, such a sequence is repeated with each of a plurality of toners of different colors to produce a multicolor toner image on the photoconductive element, an then the toner image is transferred to a paper sheet or similar recording medium and fixed thereon. This kind of method is advantageous over another conventional method which transfers a toner image to a paper sheet every time the toner image is formed so as to superpose such toner images on the paper sheet, since it reduces the deviation between successive toner images of different colors and effects image transfer only once. However, the problem with the former scheme is that at the second and successive image forming steps included in the same multicolor image forming process, the laser beam scans the photoconductive element through a toner image or images existing on the element. Hence, a desirable multicolor image is not achievable unless the same scanning effect is set up in both the area where a toner image is present and the area where it is absent. To expose both the area where a toner image present and the area where it is absent to the same degree, the intensity of the laser beam may be increased in the former area, as proposed in Japanese Patent Laid-Open Publication No. 63225/1990. However, simply controlling the intensity of the laser beam is not successful in achieving satisfactory dot reproducibility in the area where toner images overlap, since the laser beam has its intensity reduced and its diameter changed when transmitted through the toner image.